The present invention relates to a dynamic semiconductor memory device provided with an active restore circuit in which, in reading out data from a memory cell, the bit line voltage is not adversely influenced by the readout operation.
In a dynamic semiconductor memory device, a selected cell is connected to one of a pair of bit lines connected to a sense amplifier, and a dummy cell is connected to the other bit line so as to perform a readout operation. Further, an active restore circuit is connected to the pair of bit lines so that the bit line voltage is not adversely influenced by the readout operation.
That is, an active restore circuit of the above-mentioned type can ensure the detection of information in the memory cell by pulling up the bit line on the high potential side of the electric source to a power source voltage Vcc just after actuation of the sense amplifier.
However, as is described in detail hereinafter, the potential difference between the two bit lines is very small. Therefore, the sense amplifier sometimes cannot definitely distinguish the potential difference between the two bit lines, and, as a result, an error occurs in reading out the stored information.